Added InstCombine Transform for pattern "((~A & B) | A) -> (A | B)"

[suyog]

Summary

This patch implements transform for pattern "((~A & B) | A) -> (A | B)"

Please help in reviewing this patch.

[suyog]

Hi Duncan,

Added Code for Pattern "((A & B) | ~A) -> (~A | B)" as well as per your review.

Please help in reviewing the updated patch.

Thanks,
Suyog Sarda

[dexonsmith]

LGTM.

[suyog]

Closed by commit rL213676 (authored by @suyog).

llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

Instruction *InstCombiner::visitOr(BinaryOperator &I) {
   if (Op1->hasOneUse() &&
       match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
       MaskedValueIsZero(Op0, C1->getValue())) {
     Value *NOr = Builder->CreateOr(A, Op0);
     NOr->takeName(Op0);
     return BinaryOperator::CreateXor(NOr, C1);
   }
 
+  // ((~A & B) | A) -> (A | B)
+  if (match(Op0, m_And(m_Not(m_Value(A)), m_Value(B))) &&
+      match(Op1, m_Specific(A)))
+    return BinaryOperator::CreateOr(A, B);
+
+  // ((A & B) | ~A) -> (~A | B)
+  if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
+      match(Op1, m_Not(m_Specific(A))))
+    return BinaryOperator::CreateOr(Builder->CreateNot(A), B);
+
   // (A & C)|(B & D)
   Value *C = nullptr, *D = nullptr;
   if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
       match(Op1, m_And(m_Value(B), m_Value(D)))) {
     Value *V1 = nullptr, *V2 = nullptr;
     C1 = dyn_cast<ConstantInt>(C);
     C2 = dyn_cast<ConstantInt>(D);
     if (C1 && C2) {  // (A & C1)|(B & C2)

llvm/trunk/test/Transforms/InstCombine/or.ll

 ; CHECK-LABEL: @test38(
 ; CHECK: select i1 %tobool, i32 -1, i32 %x
   %tobool = icmp ne i32 %y, 0
   %sext = sext i1 %tobool to i32
   %x = load i32* %xp
   %or = or i32 %x, %sext
   ret i32 %or
 }
+
+define i32 @test39(i32 %a, i32 %b) {
+; CHECK-LABEL: test39(
+; CHECK-NEXT: %or = or i32 %a, %b
+ %xor = xor i32 %a, -1
+ %and = and i32 %xor, %b
+ %or = or i32 %and, %a
+ ret i32 %or
+}
+
+define i32 @test40(i32 %a, i32 %b) {
+; CHECK-LABEL: test40(
+; CHECK-NEXT:   %1 = xor i32 %a, -1 
+; CHECK-NEXT: %or = or i32 %1, %b
+ %and = and i32 %a, %b
+ %xor = xor i32 %a, -1
+ %or = or i32 %and, %xor
+ ret i32 %or
+}